Would someone care to offer up an explanation to the workings of EVI on copeland scrolls, it's effect on discharge pressure/temp in particular

I have one with intermittent high discharge alarms, that I'm struggling to get on top of

Help appreciated :)

Glenn Moore

20-03-2016, 12:45 AM

Hi
The EVI system is simply an economiser/subcooler to improve the system efficiency.
The economiser system is simply a small liquid subcooler in parallel with the main evaporator. The liquid line from the condenser has a tee to split the liquid feed. The main feed supplies the main evaporator TEV , whereas the side feed supplies the sub cooler TEV. So the main liquid supply to the evaporator TEV is heavily sub cooled to enhance the system duty , and the suction outlet from the sub cooler is fed into the compressor scroll set, half way through the compression cycle (economiser port). This has the effect of improved compressor capacity and also helps to reduce the discharge temperature (superheat) .
So check the main TEV superheat setting and the setting of the subcooler TEV and its function.The control of the subcooler could be causing your problem

Magoo

20-03-2016, 01:37 AM

Hi Glenn.
great explanation of current tech., and I fully understand. BUT totally beyond Joe average in the feild.
Unfortunaltely.
I do wonder why the initial installer is not servicing system, most likely owner wants a cheap service job to save money. Whats new.

RANGER1

20-03-2016, 04:59 AM

Hi all

Long time no post for me...

Would someone care to offer up an explanation to the workings of EVI on copeland scrolls, it's effect on discharge pressure/temp in particular

I have one with intermittent high discharge alarms, that I'm struggling to get on top of

Help appreciated :)

Can you give us some relevant conditions system running at pressures, superheats, also at compressor suction, discharge temperature, alarm & trip setpoints, refrigerant, what it is cooling, type of condenser.

jdunc2301

20-03-2016, 03:59 PM

Thanks Glenn, Makes more sense now.

I've got a gut feeling its the control behind it all causing the issue....considering there are no set points coming up relating to the EEV. Knowing my luck its the wrong control fitted.